This invention relates to spread-spectrum cellular and non-cellular communications, and more particularly to the 3rd generation (3G) system or 4th generation (4G) system wherein a remote station may use the 3G or 4G system as either a circuit-switched network or as a packet-switch network.
The 3rd generation system employs circuit-switched (CS) remote stations which transmit voice, or data, as continuous data, and packet-switched (PS) remote stations which transmit packets of data in an irregular, bursty manner. The PS-remote stations, for example, might be accessing the Internet, with irregular packets of data. The PS-remote station and the CS-remote station may reside in a common transceiver, or common transmitter and receiver.
If too many CS-remote stations used a particular base station, then the PS-remote stations are blocked from the base station because of lack of available capacity in the spread-spectrum channels assigned to the base station. When a PS-remote station enters the cell, this PS-remote station initially may transmit too much power and jam the transmissions from the CS-remote stations. If a power ramp-up procedure were used by the PS-remote station in order to avoid jamming the CS-remote stations, then the header portion of a packet from the PS-remote station typically is sent several times until a link is established, which increases the duration of the packet and significantly reduces the efficiency of a packet-switched system.
A general object of the invention is efficient sharing of system capacity of a 3G system cell, or a 4G system cell, between CS-remote stations and PS-remote stations.
Another object of the invention is to allow the PS-remote station to be located within the system so that calls to the PS-remote station go to the correct base station for transmission to the mobile PS-remote station.
According to the present invention, as embodied and broadly described herein, an improvement to a spread-spectrum, code-division-multiple-access (CDMA) system is provided, comprising one or more cells, with each cell containing multiple circuit-switched (CS) remote stations, and multiple packet-switched (PS) remote stations and a base station capable of transmitting circuit-switched signals and packet-switched signals. A CS-remote station transmits a spread-spectrum CDMA signal, with a chip rate fc, with a CS-symbol rate of fb, and with a power level PCS. A PS-remote station transmits a spread-spectrum CDMA signal with the chip rate of fc, with a PS-symbol rate fp, and with a power level PPS.
Assume that a plurality of CS-remote stations communicates with a particular base station. A PS-remote station can communicate with the base station provided that (1) a packet channel is available, (2) there is available capacity in the spread-spectrum channels at the base station, (3) the required data rate is available, (4) the base station provides the PS-remote station a chip-sequence signal for communicating with the base station, and (5) the base station provides the PS-remote station a power level for the PS-remote station to transmit to the base station. For efficient sharing of system capacity in the spread-spectrum channels at the base station, between the CS-remote station and the PS-remote station, the power level PPS from the PS-remote station and the power level PCS from the CS-remote station are related by: E=PPS/fp=PCS/fb, in which the energies E are the same, or PPS/fp=kPCS/fb, in which the energies E differ by a factor k. If kxe2x89xa01, then the error rates in the circuit switched system will differ from the error rates in the packet switched system.
Additional objects and advantages of the invention are set forth in part in the description which follows, and in part are obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention also may be realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims.